Paul;
How little you guys know about the US. Three of the "States" you name are really "Commonwealths". The United States is a true misnomer perpetuated by - the US. It is a mixture of States and Commonwealths. They differ in a rather complex manner in the manner in which they are governed.
PE
This is probably off topic, if you want further comments then I'd be pleased to discuss it off list, PM me if interested. I will say though that for this purpose I don't think there is a real difference between a state and a commonwealth.
Now dragging this kinda back on topic, companies like Freestyle, can easily use logistics to fix this for Canadian and other countries, let me explain.
How logistics works is this, sending a package worth $25 to say Canada from the US means sometimes a $50 brokerage charge (DHL is famous for this). So what they do, is they send the package to the logistics company, they load your packages with others from other companies into a truck trailer or container going to the destination country. This is sent as a single shipment through customs with a manifest that details what is in the trailer/container. This means a single brokering, and a single customs fee. Once the trailer/container is across the border, it's inducted at a domestic carrier who delivers it.
Along with this, you set up a destination country web catalogue, so it's as if your domestic in that country.